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Today's Topics:
1. Changing the USRP N210 FPGA clock frequency
(Jinu Jayachandran via USRP-users)
2. Re: Mis-aligned data on B210 RX channels
(Robert Kossler via USRP-users)
3. using uhd_fft with USRP N210 (tides anugraha via USRP-users)
4. Re: Mis-aligned data on B210 RX channels
(Stefan Ereth via USRP-users)
5. USRP2+WBX LO leakage TX (Andrea Mariani via USRP-users)
6. Re: USRP2+WBX LO leakage TX (Mike Jameson via USRP-users)
7. Re: USRP2+WBX LO leakage TX (Martin Braun via USRP-users)
8. Re: USRP2+WBX LO leakage TX (Marcus D. Leech via USRP-users)
----------------------------------------------------------------------
Message: 1
Date: Mon, 19 May 2014 21:42:37 +0530
From: Jinu Jayachandran via USRP-users <[email protected]>
To: "[email protected]" <[email protected]>
Subject: [USRP-users] Changing the USRP N210 FPGA clock frequency
Message-ID:
<CAKmcSybsSAkJYTpwgBf=djcqkoz4kcmopipzeo_vvstucyz...@mail.gmail.com>
Content-Type: text/plain; charset="utf-8"
Hi,
I am working on the Xilinx FPGA in USRP N210. I am trying to implement an
OFDM transceiver in two different USRP FPGAs (one as transmitter and other
as receiver).
I would like to implement the module between DUC/DDC chain and VITA
TX/RX. I am using the custom_dsp_rx.v and custom_dsp_tx.v files.
I am stuck in the part where I want to convert the parallel data to
serial. The input data received in the custom module is 16-bit I (and
16-bit Q) samples. So I need a clock frequency 16 times to that of base
clock frequency (i.e 100MHz x 16 = 1.6GHz) which is not possible in the
Spartan 3A-DSP FPGA. So is it possible to reduce the original frequency of
FPGA from 100MHz to 10MHz, so that I can multiply this frequency by 16 for
serial conversion ?. Or is there any other method to do the same ?
Please Help
Regards,
Jinu
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Message: 2
Date: Mon, 19 May 2014 12:58:54 -0400
From: Robert Kossler via USRP-users <[email protected]>
To: Ben Hilburn <[email protected]>
Cc: "[email protected]" <[email protected]>
Subject: Re: [USRP-users] Mis-aligned data on B210 RX channels
Message-ID:
<[email protected]>
Content-Type: text/plain; charset="utf-8"
Sorry, for the delay ? I have been away for a week or so. Here is the
attachment. Has anyone seen a similar linear phase versus frequency behavior?
Rob
From: Ben Hilburn [mailto:[email protected]]
Sent: Wednesday, May 14, 2014 5:16 PM
To: Robert Kossler
Cc: [email protected]
Subject: Re: [USRP-users] Mis-aligned data on B210 RX channels
Hi Robert -
It looks like your attachments may have gotten stripped. Can you try re-sending
them?
Cheers,
Ben
On Wed, May 7, 2014 at 2:28 PM, Robert Kossler via USRP-users
<[email protected]<mailto:[email protected]>> wrote:
I am using a B210 to collect data from 2 RX channels simultaneously and saving
the results to file (using a modified program based on "rx_samples_to_file").
As a test, I injected a multi-tone signal (400 tones evenly spaced across 20
MHz) into both RX ports using a 1:2 splitter. I then computed FFTs and
compared the relative magnitude and phase of each tone between the two
channels. The magnitude was nearly equal as expected. But, the phase has a
linear drift with frequency. During one capture, the relative phase between
adjacent tones (tone spacing of 50 kHz) was 79 degrees. But, the phase slope is
not constant from capture to capture.
For the capture where I measured 79 degrees between adjacent tones, I
calculated that this amount of linear phase versus frequency corresponds to a
channel-to-channel time delay of about 4.39 us, which in turn corresponds to
about 110 samples at my sampling rate of 25 MS/s. Indeed, when I purposely
shift one of the channels by 110 samples, the linear phase versus frequency
disappears.
I am wondering if anyone has seen similar behavior. I fully expect that the
problem is some type of configuration problem or some problem in interpreting /
saving the incoming data streams but I can't seem to find it.
Attached is my "rx_samples_to_file_2" code which is a combination of the
"rx_samples_to_file" and "benchmark_rate" examples programs.
Rob Kossler
_______________________________________________
USRP-users mailing list
[email protected]<mailto:[email protected]>
http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com
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Message: 3
Date: Tue, 20 May 2014 11:07:30 +0700
From: tides anugraha via USRP-users <[email protected]>
To: [email protected], [email protected]
Subject: [USRP-users] using uhd_fft with USRP N210
Message-ID:
<CA+a=GO50Eu3uB=pewdazm5z12rf8maq-938ddaodneesqxh...@mail.gmail.com>
Content-Type: text/plain; charset="utf-8"
Hi,
I,m trying to run uhd_fft with USRP N210, my machine run Ubuntu 12.04.4
LTS. I've already install UHD, gnuradio, & OpenBTS in my machine & works
fine.
But when i try to run uhd_fft which is in
/var/opt/gnuradio-3.7.0/gr-uhd/apps directory, i've got the following
message:
root@OpenBTS:/var/opt/gnuradio-3.7.0/gr-uhd/apps# ./uhd_fft
Traceback (most recent call last):
File "./uhd_fft", line 23, in <module>
from gnuradio import gr, gru
ImportError: No module named gnuradio
I've already try to run make & make install command in
/var/opt/gnuradio-3.7.0/build/gr-uhd directory, as suggested in previous
discussion, but it still show the same result.
Can anyone help to solve this issue.
Thanks,
Tides
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Message: 4
Date: Tue, 20 May 2014 10:07:59 +0200
From: Stefan Ereth via USRP-users <[email protected]>
To: Robert Kossler <[email protected]>
Cc: "[email protected]" <[email protected]>
Subject: Re: [USRP-users] Mis-aligned data on B210 RX channels
Message-ID: <[email protected]>
Content-Type: text/plain; charset="utf-8"
Hi Robert,
I have a similar problem with the B210. What do you mean with the phase slope
is not constant from caputre to capture? Do you mean after restarting your
programm and writing a new file? I find out, that by my setup the channel
assignment differs after retuning b210/restarting program?
Could you please test, if the channel assignment is right? Connect your signal
to one channel and let the other open. Try this for at least 20 times.
Regards ,
Stefan
----- Original Message -----
From: "Robert Kossler via USRP-users" <[email protected]>
To: "Ben Hilburn" <[email protected]>
Cc: "[email protected]" <[email protected]>
Sent: Monday, May 19, 2014 7:01:54 PM GMT +01:00 Amsterdam / Berlin / Bern /
Rome / Stockholm / Vienna
Subject: Re: [USRP-users] Mis-aligned data on B210 RX channels
Sorry, for the delay ? I have been away for a week or so. Here is the
attachment. Has anyone seen a similar linear phase versus frequency behavior?
Rob
From: Ben Hilburn [mailto:[email protected]]
Sent: Wednesday, May 14, 2014 5:16 PM
To: Robert Kossler
Cc: [email protected]
Subject: Re: [USRP-users] Mis-aligned data on B210 RX channels
Hi Robert -
It looks like your attachments may have gotten stripped. Can you try re-sending
them?
Cheers,
Ben
On Wed, May 7, 2014 at 2:28 PM, Robert Kossler via USRP-users <
[email protected] > wrote:
I am using a B210 to collect data from 2 RX channels simultaneously and saving
the results to file (using a modified program based on "rx_samples_to_file").
As a test, I injected a multi-tone signal (400 tones evenly spaced across 20
MHz) into both RX ports using a 1:2 splitter. I then computed FFTs and compared
the relative magnitude and phase of each tone between the two channels. The
magnitude was nearly equal as expected. But, the phase has a linear drift with
frequency. During one capture, the relative phase between adjacent tones (tone
spacing of 50 kHz) was 79 degrees. But, the phase slope is not constant from
capture to capture.
For the capture where I measured 79 degrees between adjacent tones, I
calculated that this amount of linear phase versus frequency corresponds to a
channel-to-channel time delay of about 4.39 us, which in turn corresponds to
about 110 samples at my sampling rate of 25 MS/s. Indeed, when I purposely
shift one of the channels by 110 samples, the linear phase versus frequency
disappears.
I am wondering if anyone has seen similar behavior. I fully expect that the
problem is some type of configuration problem or some problem in interpreting /
saving the incoming data streams but I can't seem to find it.
Attached is my "rx_samples_to_file_2" code which is a combination of the
"rx_samples_to_file" and "benchmark_rate" examples programs.
Rob Kossler
_______________________________________________
USRP-users mailing list
[email protected]
http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com
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Message: 5
Date: Tue, 20 May 2014 08:18:42 +0000
From: Andrea Mariani via USRP-users <[email protected]>
To: "[email protected]" <[email protected]>
Subject: [USRP-users] USRP2+WBX LO leakage TX
Message-ID:
<ec2871fbdfd739408ed8e71329989799013ecc7...@e10-mbx4-dr.personale.dir.unibo.it>
Content-Type: text/plain; charset="iso-8859-1"
Dear all,
I'm getting started with some transmission test using USRP2+WBX daughterboard,
based on simple OFDM like signals.
I'm experiencing a DC offset in the transmitted signal, which I think is caused
by a LO leakage problem.
How could I remove it?
Is there an alternative to "manually" removing the DC offset?
Thanks in advance.
PS: regarding WBX documentation I didn't find so much on the ettus website,
where can I found it? Thanks!
------------------------------
Message: 6
Date: Tue, 20 May 2014 10:18:13 +0100
From: Mike Jameson via USRP-users <[email protected]>
To: Andrea Mariani <[email protected]>
Cc: "[email protected]" <[email protected]>
Subject: Re: [USRP-users] USRP2+WBX LO leakage TX
Message-ID:
<CAJcjmiTCftBuXrZskXM=hyjlnyypc1ovtyjk-qt_jdnimao...@mail.gmail.com>
Content-Type: text/plain; charset="utf-8"
Put the following line in the "Center Freq" box of the "UHD Source" block
in GRC:
uhd.tune_request(center_freq, rf_freq=(center_freq +
lo_offset),rf_freq_policy=uhd.tune_request.POLICY_MANUAL)
You must define the variables 'center_freq' and 'lo_offset'. lo_offset
should be outside the passband i.e. (samp_rate/2) * 1.25
Mike
--
Mike Jameson M0MIK BSc MIET
Ettus Research Technical Support
Email: [email protected]
Web: http://ettus.com
On Tue, May 20, 2014 at 9:18 AM, Andrea Mariani via USRP-users <
[email protected]> wrote:
> Dear all,
>
> I'm getting started with some transmission test using USRP2+WBX
> daughterboard, based on simple OFDM like signals.
> I'm experiencing a DC offset in the transmitted signal, which I think is
> caused by a LO leakage problem.
> How could I remove it?
> Is there an alternative to "manually" removing the DC offset?
>
> Thanks in advance.
>
> PS: regarding WBX documentation I didn't find so much on the ettus
> website, where can I found it? Thanks!
>
> _______________________________________________
> USRP-users mailing list
> [email protected]
> http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com
>
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Message: 7
Date: Tue, 20 May 2014 13:40:59 +0200
From: Martin Braun via USRP-users <[email protected]>
To: [email protected]
Subject: Re: [USRP-users] USRP2+WBX LO leakage TX
Message-ID: <[email protected]>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
On 20.05.2014 10:18, Andrea Mariani via USRP-users wrote:
> Dear all,
>
> I'm getting started with some transmission test using USRP2+WBX
> daughterboard, based on simple OFDM like signals.
> I'm experiencing a DC offset in the transmitted signal, which I think is
> caused by a LO leakage problem.
> How could I remove it?
> Is there an alternative to "manually" removing the DC offset?
>
> Thanks in advance.
>
> PS: regarding WBX documentation I didn't find so much on the ettus website,
> where can I found it? Thanks!
Our general d'board manual page is here:
http://files.ettus.com/uhd_docs/manual/html/dboards.html
And you can find the schematics here:
http://files.ettus.com/schematics/wbx/
Cheers,
Martin
------------------------------
Message: 8
Date: Tue, 20 May 2014 09:13:58 -0400
From: "Marcus D. Leech via USRP-users" <[email protected]>
To: [email protected]
Subject: Re: [USRP-users] USRP2+WBX LO leakage TX
Message-ID: <[email protected]>
Content-Type: text/plain; charset="utf-8"; Format="flowed"
On 05/20/2014 05:18 AM, Mike Jameson via USRP-users wrote:
> Put the following line in the "Center Freq" box of the "UHD Source"
> block in GRC:
>
> uhd.tune_request(center_freq, rf_freq=(center_freq +
> lo_offset),rf_freq_policy=uhd.tune_request.POLICY_MANUAL)
>
> You must define the variables 'center_freq' and 'lo_offset'.
> lo_offset should be outside the passband i.e. (samp_rate/2) * 1.25
>
> Mike
Or, even simpler:
uhd.tune_request(target_frequency_in_hz, desired_lo_offset)
--
Marcus Leech
Principal Investigator
Shirleys Bay Radio Astronomy Consortium
http://www.sbrac.org
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End of USRP-users Digest, Vol 45, Issue 18
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